<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>正则扩展-反向断言</title>
</head>
<body>
    <script>

        // TODO 可以根据目标内容的前面或者后面的内容进行唯一性的识别
        //声明字符串
        let str = 'JS5211314你知道么555啦啦啦';
        //正向断言
        const reg = /\d+(?=啦)/;
        const result = reg.exec(str);

        //反向断言
        const reg = /(?<=么)\d+/;
        const result = reg.exec(str);
        console.log(result);
    </script>
</body>
</html>